Where is the difficulty?
The difficulty is in the incorporation of the categorical
variables into the model. There are various approaches to use
categorical variables in traditional regression models such as
linear and logistic, and these approaches can also be used
in NN.

But how to use them in fuzzy models? A possible solution may be
to construct segmentations (like tree) using the categorical variables
and then build models in each segmentation. But you will see that this
approach is not practical when the number of categorical variables is
large (say 10) and the numner of the items is large (such as zip code).